The Science of Animal Friendships: How Beasts Can Be BFFs

This week's TIME cover story — available to subscribers here — reveals that true friendship, marked by generosity, sacrifice and commitment, once thought to be the province of humans, exists among the lower species too.

It can be a humbling time to be a Homo sapiens — or at least a vain Homo sapiens. As the planet’s reigning species, we’ve lost count of all of the remarkable abilities we possess that elevate us above the other beasts — language, tool use, empathy, arithmetics. The problem is, the more closely evolutionary biologists study animals, the more they discover that at least some nonhuman species exhibit the very same talents, even if in a rudimentary way.

Ah, but of course, humans still own friendship. Animals might be capable of companionship, caretaking and loyalty to the herd, flock or pride, but surely that’s just biology at work. They protect kin to protect their genes. They do favors for unrelated individuals because they expect a favor in return — a clinical transaction known as reciprocal altruism. What’s missing is the true generosity, communication, long-term commitment and sacrifice that defines human friendship, right? Wrong — and a growing field of science, which we report in this week’s TIME cover story (available to subscribers here), is turning up all kinds of extraordinary proof.

Take the pair of wild chimps known as Hare and Ellington, unrelated males who would hunt together, share food and hoot in communication over great distances when they were separated. A favor done by Hare today might not be returned by Ellington for months — far longer than the quick quid pro quo of reciprocal altruism. The favor was, well, just a favor. And then, too, there was the deep period of what could only be described as mourning that Hare went through when Ellington died.

Or take the three old female dolphins in Sarasota Bay — Nicklo, Squiggy and Black Tip Double Dip, who would spend hours, indeed whole days, swimming, playing and resting in one another’s close company. The trio would hunt fish together too — which can be nothing but a feeding tactic, since dolphins that cooperate better eat better as well. But it was the serene Golden Girls time they shared that seemed the true marker of their friendship.

Across the animal kingdom — among baboons, rhesus monkeys, horses — investigators are discovering similar improbable relationships that play out in many of the rich, sustained ways our own friendships do. And scientists have barely begun looking at the mysteries of cross-species bonds — the tortoise and the hippo, the cat and the crow, the pig and the monkey. How can animals that are so different draw so close? How can predator befriend prey?

The more we learn about animal friendships, the more we can understand the bonds unrelated humans share. And since friendships are known to improve longevity and reduce disease rates, the same research could also help us live longer, healthier lives.